This invention relates to the sorting of particulate material and has particular, but not exclusive, application to sorting of ore rocks.
It is known to sort ore rocks by passing the rocks one by one past a detector which determines the degree to which each rock possesses a required characteristic and then diverting or deflecting individually selected rocks from a main stream. The rocks may for example, be projected in a free flight path and the selected rocks deflected from that path by air blasts or other deflection means. This method of sorting is very accurate but requires very large and expensive apparatus to achieve a high throughput of material.
The present invention provides a method and apparatus whereby particulate material can be selected on a bulk basis rather than on a particle by particle basis. There are many applications where such bulk sorting is satisfactory, particularly when dealing with material of relatively small particle size. The present invention enables sorting to be carried out in such cases with relatively small and inexpensive equipment.